Automatic coin return system



May. l, 1945- R. c. AVERY AUTOMATIC COIN` RETURN SYSTEM Filed sept. 2s, 1943 @SK snew L -HllHlI- INVENTOR j?, @erg ATTORNEY 1 IIII lllli Patented May l, 1945 AUTOMATIC COIN RETURN SYSTEM Robert C. Avery, Jackson Heights, N. Y., assignor p to American Telephone`and`Telegraph Company, a corporation of New York i Application September 23, 1943, Serial No. 503,498

6 Claims.

This invention relates to a crossbar dial telephone system and particularly to means forautomatically returning to a pay station user'the coin deposited by him for the making of a call when that pay station line is under lineload control.

In order to limit the number of calls that may be placed at any onetime by the subscribers or users of telephones in a given central oilice district which would interfere with the handling of essential traillc through that central ofce, there has been developed and put into 'service a system of traliic regulation known as lineload control. By means of thatsystem` it is possible to prevent users of telephones, upon which the lineload control feature is impressed, from establishing atelephone connectionthrough that central olce and thereby-prevent an overloading of the linesand the switching facilities of that central oillce in the event that an abnormal number of calls origi-` mated-at the same time, which is `possible and highly probable under emergency conditions such as may occur duringla state of war.

'I'he present invention is concerned with a particular feature of the lineload control system,

namely, means for insuring the return of the coin or coins deposited in a prepayment coin collect telephone by a user attempting to make a call during the time in which the lineload control is in operation. `This invention will be clearly understood from the following descriptiony'when read in connection with the attached drawing which shows schematically one form of embodiment of the invention.

In the drawing, the apparatus within the dot and dash lines, shown inthe upper left-hand corner whenthe drawing is `viewed from `the right-handside, represents a prepayment coin collect station which. station is connected by the line L1 to the apparatus at the central oflice, part of which represents the standard apparatus of a crossbar dial switching system and the remainder of the apparatus,` which is shown in greater detail, represents that in which the invention is embodied. l

The coin collect station whichfas shown, is a standard type of the Bell system, comprises an induction coil I, aringer- 2, a receiver 3, aj hook switch 4, a transmitter 5, a coin relay 6 having associated therewith a coin contact 'I, azdial 8 and' a filter 9. The function of this apparatus, in so far as it is necessary for the description of the present invention, will be more fully described hereinafter. 'I'he telephone station is connected by the line L1 to the crossbar central LSI oiiice a portion of which is represented symbolically by the apparatus designated I0 within the dotted lines, comprising the hold magnet and a plurality of select magnets in the line link frame of the well-known crossbar dial switching system. VSuch a system is described in a paper entitled, Crossbar Dial Switching System, by Scudder and Reynolds, published in the Bell System Technical Journal, volume 18 (1939), page 76et seq.` In such a line link frame a hold magnet is associated with each line and the connection is extended into the subsequent switches of the system by operationof'oneof the select magnets shown, under control of suitable apparatus. Since the remainder of the apparatus through which the call would normally pass were the line not under lineload control is fully-de# scribed in that paper and forms per se ncpart of this invention, detailed description is unnec' essary. l

The lineload control circuit includes a common control `circuit which includes a manually oper atedswitch Il, a relay I2 anda lamp I3. Relay `I2 controls an auxiliary 'control relayH through the contacts of which a plurality of lineload control relays; such as I5, may in turn be controlled. Ihe connection between relays I4 and I5 is established by a locking type key 46 at the control frame.- The lineloadcontrol relay I5 has a plurality of armatures and contacts certain of which are connected with the apparatus shown on the drawing, and the others of which are intended to establish connections for appara# tus for other lines, similar tothat shown upon the drawing. 'I'he armature I6 of relay I5 is connected to the armature of the line relay I"I, and the upper contact of that line relay is connected by conductor I8 to the' armature I9 of relay I5. The upper contact of armature I5 is connected by conductor 20l to the innerarmature of the hold' magnet 2I, which armature normally makes a elo-sed contact with the tip side of `the line Li. The outer armature of relay 2|- is connected to one terminal of the winding of relay I1 and the other terminal of that windingV is connectedv to the normally, closed contact of relay22. The 'left-` hand armature of that relay hasconnected therewith a battery 23 whi-ch batteryis also connected to the winding of relay 22 and serves to operate that relay whenever relay 24 i`s operated. The inner right-hand armature of relay 22 vhas con'' nected thereto battery 25. Thecontact of that armature is connected to one "terminaloffthe" winding of relay 24 and the other terminal thereV of is connected by conductor 26 to `the lower con#l tact of armature I6 of the lineload control relay I5. The outer right armature of relay 22 is connected to ground and its conta-ct is connected to a circuit that includes lamp 21 and the battery 28.

The manner in which the system operates to perform the function that the present invention is designed to perform, is as follows: Let it be assumed that. the conditions are such as to necessitate the exercising of lineload control over the group of lines within which the coin collect sta tion connected to the line L1 would belong. The attendant at the dial switching oiiice would operate the master key II and thereby 'would operate relay I2, and also would operate key 46, which is subordinate to the keyA II', and controls the particular group of lines involved. That relay would be locked by a circuit extending from battery 29, through contact 30 of relay I2 and thence over conductor 3| and the contact 32 of arrna` ture 33 of relay I5 as soon as the latter relay has operated'. The operation of that relay is effected in'. the following manner: U'pon the closing of contact 34 of relay' I2, relay I4 will operate and that will' place a ground upon the winding of relay I5l assuming that the key 46 at the control by removing the receiver 3 from the hook. The 1' coin contact 'I will'be closed in the usual manner when the coin is dropped intoA the slot and a circuit will be established from ground that will include the contact 1, the windings of the coin relay 6, contact 36 of the hook switch, conductor 31; contact 38' of the dial, conductor 39, transmitter 5, the winding' 46 of the induction coil I, the ring' side of the line, contact 4I of the hold magnet'2I the winding ofrelay I1, the left-hand contact of'relay 22 and battery 23 to ground. The

flow of current over the circuit just traced will operate theY line relay I1 but it will not operate the coin relay 6 to effect the return of the coin to the user of that station. That act, however, will follow almost instantly upon the operation of' the line relay I1. When that relay operates andl closes' its contact 42 a. circuit will be established from `the battery 25 which is connected to the right-hand inner armature of relay 22, which circuit'would include the contact of that armature, the winding of relay 24, conductor 26, the lower contact of armature I6 of relay I5, contact 42of relay I1, conductorv I8, the inner contact of armaturev I9, conductor 20, the Contact of the inner armature of hold magnet 2I, the tip side of the line L1, conductors 43v and 44 of the telephone'station, coin relay 6, contact 1 and ground. That current is of sufficient strength to operate the coin relay-6. and thereby to cause the return ofthe cointo the user of that station. The ilow ofrv current through the winding of relay 24 will cause' that relay'to operate and will put a ground uponthe' winding of relay 22 which would cause the operation of the latter relay. Upon the operation of relay 22 the contacts'of its left-hand armature and its innerv right-hand armature are opened; The opening of the left-hand Contact opens the circuit through the winding of line relay I1 and causes the release of that relay;

The' ,opening of the right-hand contact of the inner armature opens the circuit through the relay 24 thereby causing that relay to release which removes the ground from the winding of relay 22. The opening of the right-hand contact of relay 22 also discontinues the flow of current over the tip side of the line and through the Winding of the coin relay 6. The operation of relay 22 also 4closes the contact of the outer righthand armature of that relay which in turn would cause the lighting of the lamp 21 which lamp serves to indicate to the attendant the operation of relay 22. Ordinarily the lighting of that lamp would be disregarded. It serves as an indicator of trouble upon the line as, for example, the

accidental grounding of Iboth conductors of the line` or ofV one conductor, and the removal of the receiver -at the station. Under those conditions the lamp would flash until the trouble was 1ocated and removed.

If the user of the prepayment coin collect station attempted to repeat the call by again inserting a coin in the slot during the continuance of lineload control over that station, the system would again operate in the manner just described, that is, the line relay I1 would operate and the circuit would be closed from the battery 25 to the tip side of the line and thence through the coin relay 6 to ground, thus causing the operation of that relay and the return of the coin again to the user.

As soon as conditions return to normal, so as to permit restoring to service the group of lines containing the line illustrated here', key 46 would be released and relay I5 would be deenergized thus permitting its armatures'to fall back to their normal positions. Contact 32 would be opened and' relay I2' would be 'released upon release of all lineload control relays such as relay I5. That, in turn, would releasel relay I4' of the common control circuit. Thevcircuit that extended from the battery 25 dver the tip side ofI the line L1 and through the coin relay 6, by which that re'- lay was heretofore operated, would bev opened when the armatures I6 and' I6return to normal and, consequently, the operation ofthev coin relay 6, for the` collectionv or the return of the coins deposited at that station, would be normally under the control of apparatus' that forms partof the crossbar dial switching system. Relay 22', by which current for thevoperation of the line relay and the coin'relay is applied to the several circuits, is designed to be sufficiently slow in operation in order to allow the necessary time for the full operation of the coin relay'a't the pay station. Relay 22 is also designed for slow' release in order to permit the lamp 21 to be lighted' fora suicient time to be noticeable.

While this invention has been described as em` bodied in a particular form and arrangement of' parts, it is capable of embodiment in otherand different forms without departing from the spirit and scope of the appended claims.

What is claimed is:

1. In a crossbar dial telephone system, the combination with a lineload control circuit adapted to be operated at will, of a line relay, a pay station having a coin relay associated therewith, the said coin relay having a' contact adapted to be closed by the presence of: a coin, and al coin' return control circuit having a `relay 'associated therewith adapted to apply current to the said line relay whenever the said coin contact at the paystation has been closed and the receiver thereat has been removed from its hook; anda second source of current also controlled by the saidl relay of the coin return control circuit adapted to apply to the coin relay a voltage of such polarity and such' magnitude as to effect the return of any coins deposited while the lineload control circuit is operated. y

2. In a crossbar dial telephone system arranged for lineload control, the method for automatically returning the coins deposited in a pay station telephone Whenever the system is under lineload control, which consists in operating the lineload control relay thereby closing a path from a source of current to the contacts of the line relay, automatically operating said line relay by the grounding of the line by depositing a coin, Whereby current is caused to iiow from the said source through the coin relay of the said telephone set, the current being of such polarity and such strength as to operate the coin relay in such direction as to return the coin.

3. In a crossbar dial telephone system characterized byl the provision of means to control the lineload thereof, the method of returning coins to users of prepayment coincollect telephones whenever lineload control is applied to the system, which consists in operating the lineload control relay, grounding the line by inserting a coin in the coin collect telephone, automatically transmitting current through the line relay connected to one side of the grounded line to effect the operation of that relay and thereby to close another circuit between the said coin relay and a source of current of such magnitude and polarity as to effect the operation of the coin relay and the return of the deposited coin.

4. In a crossbar dial telephone system characterized by the provision of means to control the lineload thereof, the combination with a pay station telephone connected by a line to a dial central office, the said pay station having a coin relay connected thereto, of a line relay at thesaid oce, one terminal of the windingof which is connected to one side of A the said line, a coin return relay arranged to connect a source of current to the winding of the said line relay whenever the coin contact is closed at the said pay station, another source of current also associated with `the said coin return relay arranged `to be connected to the coin relay at the pay station whenever the said linerelay is operated, the said other source of current being of such magnitude and polarity as to eiect the operation of the coin relayv and the return of the coin at the pay station. ,i

5. In a crossbar dial telephone system characterized lby the provision of meansto control the lineload thereof, the combination with a pay station telephone connected by a line to a dial central office, the said pay station having a coin relay connected thereto, of a line relay at the central olli-ce, one terminal of the Winding of which is connected to one side of the said line, a coinreturn relay arranged to connect a `source of current to the winding of the said line relay and to eiect its operation whenever the coin contact is closed at the pay station, another source of current, also associated with the said coin return relay, arranged to be connected to the coin relay at the pay station Whenever the said line relay is operated, the said other source of current being of such magnitude and polarity as to elect the operation of the said coin relay and thereturn of the coin, and a disconnect relay operable by the current flow from the saidl other source of current to effect the deenergization of the said coin return relay within a predetermined time after the operation of the latter relay.`

6. The system defined by claim 5 further characterized by the provision of a signal to be operated upon each operation of the said coin return relay to indicate such operation.

ROBERT c. AVERY. 

